1. Field of the Invention
This invention relates to a high-intensity light source for a fiber optics illumination system for applying light from a high-intensity light source along a predetermined path for illuminating one end of a fiber optics illumination conduit or light conduit. More specifically, the present invention relates to a high-intensity light source for a fiber optics illumination system wherein an axial flow, propeller-type impeller, that is, a fan, is positioned to have its vanes rotated through the gap between the lamp and the light conduit and the light is directed along the predetermined path onto one end of a fiber optics illumination conduit.
2. Description of the Prior Art
High-intensity light sources for fiber optics illumination systems are well known in the art. Typical of the fiber optics sources known in the art are those described in U.S. Pat. Nos. 3,775,606 and 3,733,481. The fiber optics light console disclosed in U.S. Pat. No. 3,775,606 relates to a light source which includes a dual illumination system which permits simultaneous use of two cables with the same console and which enables the user to switch from one cable to another cable in the event of failure of one light source during a surgical operation. The light console employs light and heat shielding means surrounding each of the light sources, and the shielding means function as a heat sink. Preferably, the shielding means may be air cooled to protect the front portion of the console to reduce the temperature thereof. The light console is air cooled by a fan-type motor with the motor located rearward of the light source and the bayonet-type mounting apertures which are adapted to receive ends of fiber optics light cables.
U.S. Pat. No. 3,733,481 discloses a fiber optics light source which includes a lamp house including a lamp, reflector and condenser aligned for focusing light into the receiving end of a fiber optics bundle and which utilizes an air impeller mounted laterally of the lamp house to direct air over the lamp for dissipating heat build-up.
It is also known in the art to position one end of a fiber optics bundle a predetermined distance from a light source forming a gap therebetween to permit the light from the light source to be received by the one end of the fiber optics bundle and transmitted therethrough to illuminate the fiber optics bundle. Typical of such light sources are those described in U.S. Pat. Nos. 4,128,332 and 3,497,981.
It is also known in the art to position a filter, or the like, between a high-intensity light source and the one end of a fiber optics bundle in order to control the wavelength of light applied to one end of the fiber optics bundle. One such device is disclosed in U.S. Pat. No. 4,236,191 wherein a fiber optics bundle is positioned at a predetermined space from a light source, and a color wheel having a plurality of transparent colored areas formed of glass and suitable plastic mounted for rotation proximate the light bulb and intermediate the light source and the end of the fiber optics bundle. The light transmitted by the fiber optics bundle is utilized to illuminate a musical instrument such as a guitar.
U.S. Pat. No. 3,536,908 discloses a fiber optics lighting system which utilizes a rotatable turntable member which is divided into light-transmitting radial segments, and the segments are rotated intermediate the gap between the end of a light source and the end of a fiber optics bundle. The rate of rotation of the rotatable member interposed between the light source and the ends of fiber optics bundles, which are disclosed in U.S. Pat. Nos. 4,236,191 and 3,536,908, is at a very low speed and is intended to present different colors which are visually observable to a viewer.
In addition to the method described above, hot mirrors, which absorb infrared and thus become hot, while reflecting visible light, have been used to reduce heat and temperature at the light-receiving end of the light conduit, but hot mirrors do not absorb enough of the infrared radiation to prevent damage to the light conduit, and hot mirrors are expensive. Cold mirrors, which reflect visible light while allowing infrared radiation to pass through, still reflect too much infrared radiation, causing damage to the light conduit.
The high-intensity light source for a fiber optics illumination system has a large number of advantages over the known prior art light sources. None of the known prior art systems disclose, suggest, or teach the use of an impeller or fan located in the gap between a light source and one end of the fiber optics bundle. The impeller displaces air heated by the light source located in the vicinity of the reflector, light source, and one end of the fiber optics bundle along a generally axial path towards the end of the fiber optics bundle and away from the light source. The air flow produces a negative pressure in the vicinity of the impeller, reflector, and light source which causes cooling of the end of the fiber optics.
None of the fiber optics light sources disclosed in U.S. Pat. Nos. 3,775,606 and 3,733,481 disclose a cooling fan having its blades disposed between the light source and the fiber optic.
The use of a rotatable color wheel is disclosed in U.S. Pat. Nos. 4,236,191 and 3,536,908 wherein a color wheel is positioned in the gap between the light source and the end of the fiber optic to filter the light, and thereby change the color of the light.
Two fundamentally different type of fiber optics, or light conduits, are employed in the art. First, and probably most widely recognized, is a fiber optic formed from carefully extruded glass filaments, or fibers, which are very fine. A plurality of such fibers are bound together into a bundle, which is glued together with an adhesive such as epoxy. Fiber optics of this type are commonly used for transmitting communications, as well as for simple transmission of light for lighting purposes. Glass fiber optics are not well suited for general illumination systems disclosed in the prior art. Glass fiber optics are quite fragile and each fiber must be coated with a protective coating, typically a fluorine-based polymer, to protect the glass fiber. The bundle of a plurality of fiber optics must then be encased in a larger sheath. As noted, the individual fibers are then glued together with an adhesive, customarily epoxy. In high intensity illumination systems according to the prior art, the bundle of fiber optics becomes too hot for the epoxy, which breaks down chemically. The epoxy then loses its adhesive properties, causing the bundle of fiber optics to lose its cohesiveness, and the individual fibers tend to separate from one another, reducing the efficiency of light transfer to the fiber optic bundle. Furthermore, a chemical product of reaction of the decomposition of many types of epoxies used in glass fiber optics is a fluorine-based acid, which eats into the glass fibers and ruins them. In addition, as the epoxy deteriorates and decomposes, it undergoes a color change from substantially transparent to amber, to yellow, to brown. This color shift causes the fiber optic bundle to absorb more infrared radiation, which is converted to additional heat, accelerating the deterioration and decomposition of the epoxy exponentially. Generally used epoxies decompose when subjected to temperatures of about 700 degrees F. or more. A few specialty epoxies, which are quite expensive, may tolerate temperatures of about 1,200 degrees F. before decomposing. The quantity of heat that the epoxy is exposed to it also a critical factor in the chemical breakdown of the epoxy. Prior art illumination systems that attempt to employ high intensity light sources cannot keep the temperature and heat low enough to prevent decomposition of the epoxy.
The second type of optic fiber is a polymerized plastic type substance, which may be any of a number of chemical compositions that are well known in the art. Such compounds are customarily formed in situ in some type of vessel, such as a length of tubing. The resulting product is a semi-solid plastic type material, which may be roughly transparent or translucent. It may be more or less flexible. It is customarily available in sizes ranging from about 3/16 inch to about 5/8 inch in diameter and in various lengths. The material is not, however, a fiber in any normal sense of the word. It is rather a semi-solid continuously linked polymer. Most such plastic light conduits melt at temperatures of about 180 degrees F. At temperatures well below the melting point, such plastic light conduits oxidize and chemically deteriorate, with readily apparent color shift from translucent to amber, to yellow, to brown. Naturally, this color shift caused by the chemical deterioration reduces the amount of light that the light conduit will conduct and reduces the color temperature and changes the color of the light transmitted through the light conduit, all of which reduce the utility of the illumination system and increase maintenance costs. Additionally, the now-darker light conduit absorbs more infrared radiation, which is converted to heat, accelerating the deterioration of the light conduit exponentially.
No generic name for such plastic based polymer light conduits is known to applicant. In this patient application, the term "light conduit" shall be a generic term that refers to any type of material designed to transmit, or conduct light through it, including glass fiber optic bundles, polymerized plastics, or other material that is or may become known.
In the prior art systems, including the patents described hereinabove, the heat from the light source makes the end of the fiber optic extremely hot, which severely reduces the life of the fiber optic. In addition, if the end of the fiber optics bundle is heated to a very high temperature, the epoxy used in the glass fibers may break down, reducing the amount of light entering into the fiber optics bundle.
It is becoming increasingly desirable in the art to use plastic fiber optics bundles in a wide variety of applications. Plastic fiber optics are even more susceptible to heat damage than bundles of glass fibers and, because of this heat damage, the number of applications in which the plastic light conduit can be used is limited primarily to applications requiring small amounts of light. Plastic or polymerized fiber optics, or light conduits, deteriorate quickly when exposed to heat and oxygen. They become quite brittle and turn brown. The brown color of the light receiving end discolors the light transmitted through the fiber optic in an unpleasing manner, and causes the fiber optic to absorb more heat and to convert more light to heat, both of which accelerate the deterioration of the fiber optic.
Many techniques have been used to reduce the amount of heat at the light receiving end of the fiber optics bundle, including filters, fans, cold mirrors, and the like, as noted above. Such systems have achieved only limited success in keeping the light receiving end of the fiber optic cool, and they reduce the amount of light received by the fiber optic.
Consequently, most fiber optic illumination systems of the prior art must use a lamp or other light source that consumes less than about 150 watts of electricity. Even ordinary household incandescent 100 watt light bulbs produce too much heat for many prior art light conduit illumination systems. A few prior art illumination systems can use light sources that consume up to about 120-130 watts of electricity, but then the light conduit must be placed relatively distant from the light source and cannot be placed near the focal point of any focusing reflector, or lens, without causing the light conduit to deteriorate rapidly from the heat.
It is important to recognize that although the prior art discloses fiber optic illumination systems, these are low intensity illumination systems that cannot transmit very much light, whereas the present invention is directed to an illumination system that can easily employ high intensity light source consuming 500 watts of electricity or more. Even using dramatically more powerful lamps, the present invention also permits placement of the light conduit at the focal point of a focusing reflector or lens.
Demand for lighting systems employing light conduits is rapidly expanding in many applications, including: use in wet places where electricity is not safe, such as in swimming pools; use in places requiring indirect lighting, such as instrument panels; use in places where the heat of incandescent light is not acceptable; use in places that are small and difficult to direct light into; and many others.
It is also known in the art to utilize a fiber optics illumination system for a wide variety of applications, such as: a pendulum light source as disclosed in U.S. Pat. No. 3,389,247; a fiber optics light source described in U.S. Pat. No. 3,382,353; an illumination device for a sign, as disclosed in U.S. Pat. No. 3,208,174; a self-luminous sign, as disclosed in U.S. Pat. No. 3,038,271; and illuminated signs, as disclosed in U.S. Pat. Nos. 2,173,371 and 2,058,900.
Therefore a need exists for a high intensity light source for a light conduit illumination system that will provide brighter lighting from a light conduit or conduits, while preventing deterioration of the light conduit resulting from excess exposure to heat and oxygen.